Factories are re‑engineering final washes to strip residual resins, silicones, dyes, and waxes without wrecking the fabric — or the effluent permit. The playbook: tailored “washing‑off” agents, disciplined bath control, and data‑checked outcomes.
The finishing line’s quiet endgame — washing and rinsing — makes or breaks fabric performance. These steps remove unreacted finishes and additives such as resin, silicone, dyes, and waxes. Skimping risks poor color fastness, altered hand and hydrophilicity, and even effluent breaches measured as COD/BOD (chemical/biological oxygen demand). Modern plants respond with tailored “washing‑off” formulations and tightly controlled baths to maximize cleanliness while protecting fibers. Indonesia’s “Green Industry” standard (Permenperin 40/2022) explicitly emphasizes efficient chemical use and wastewater quality in fabric finishing (peraturan.bpk.go.id).
Specialty washing‑off formulations
Commercial washing‑off agents blend surfactants, dispersants, chelants (metal‑binding agents), and pH‑adjusters aligned to the specific finish. Nonionic and anionic surfactants — including ethoxylated alcohols and linear alkylbenzene sulfonates — provide wetting and emulsification for oily or waxy residues (nepis.epa.gov). Cationic surfactants or conditioners may be used last to neutralize any anionic rinse agent.
Auxiliary makers stress fit‑for‑purpose selection: a “suitable washing‑off agent [must be chosen] as per the water conditions, dyes used, print design, substrate and machinery” to secure thorough removal and high colorfastness (crodaindustrialspecialties.com). Dedicated wash‑off products often add citrate or other low‑molecular acid buffers plus surfactants to complex residual resins or metallized dyes (nepis.epa.gov; patents.google.com).
One study underscored the stakes: large amounts of cleaning surfactant remained after a single water rinse, but combining a citrate buffer with a nonionic detergent (Tergitol) drove a dramatic improvement in rinsing efficiency (patents.google.com).
Baca juga: Apa itu Chemical?
What goes into the bath
Formulations in practice may include strong detergents/scourers, such as low‑foaming alkaline wetting agents (often powders) to break oils and binders; these can saponify fats and mobilize waxes. In cotton scouring, caustic soda (NaOH) is commonly used at 5–20 g/L with bath pH up to 13–14 to hydrolyze oils and waxes (textilelearner.net).
Enzymatic cleaners provide a milder route for desizing/scouring: amylases, lipases, and pectinases operate effectively at pH ~7.5–9 and lower temperatures, often reducing rinse water needs and effluent load (textilelearner.net; textilelearner.net). For example, an α‑amylase at ~1000 IU/mL (international units per milliliter) at 55–60 °C achieved full starch removal (Tegewa 6; Tegewa is a visual scale for residual starch) without the fiber damage seen with acid at 15–20 g/L (pmc.ncbi.nlm.nih.gov).
Chelating/complexing agents (e.g., citrate, EDTA, polyphosphates) bind metal ions or fixatives, while organic acids such as acetic or citric neutralize residual alkalinity and chelate multivalent ions like copper and iron from catalysts (nepis.epa.gov; atlas-scientific.com). Auxiliary dispersants — including naphthalene sulfonate‑formaldehyde condensates, lignosulfonates, and sulfonated oils — keep insoluble dyes or pigments in suspension (textilelearner.net), helping mobilize stubborn finishes. In fluoropolymer or silicone finishes, specialty “silicone wetting agents” (siliconized nonionics) improve dispersion of hydrophobic phases.
Baths also incorporate defoamers/degreasers: silicone‑based defoamers limit suds in closed jets, and fat/oil emulsifiers remove machine oil. Hard‑water stabilizers (polycarboxylates, salts) are used when feed water carries high ionic content (textilelearner.net). When water conditions are a critical variable, some plants pair chemistry choices with pretreatment strategies; pretreatment trains commonly include ultrafiltration for surface or ground water, and in such contexts ultrafiltration serves as pretreatment to downstream steps.
Custom blends and stage sequencing
In practice, washing‑off blends are custom: an anionic surfactant plus a nonionic wetting agent, a citrate buffer, and a chelating polymer is a typical stack. Multi‑stage rinses often start with a hot detergent step followed by acidic fixers (crodaindustrialspecialties.com). The synergy is the point: improved wetting, oil emulsification, particulate dispersion, and ion complexation before the final rinses.
Temperature control by fiber and finish
Temperature accelerates removal by boosting reaction kinetics and solubility of oils/waxes — but it can also drive fiber damage or dye bleed. On cotton, conventional alkaline scouring runs near boiling, 80–100 °C, with strong caustic and surfactants (textilelearner.net). That regime fully hydrolyzes oils, waxes, and pectins, but is harsh. Enzymatic bio‑scours operate at ~50–65 °C, saving energy and preserving strength (textilelearner.net), and one cotton study found optimal enzyme desizing at 60 °C (pmc.ncbi.nlm.nih.gov).
Guidance emerges: for cotton pretreatment using alkali/scour agents, ~90 °C at about pH 12 is typical; with enzymes or delicate finishes, 50–65 °C is often sufficient (textilelearner.net; pmc.ncbi.nlm.nih.gov).
For synthetics, polyester or nylon coatings are commonly cleaned at lower temperatures (50–60 °C) to protect finishes; some flame‑retardant fabrics show crosslinker reversion even at 60–80 °C. One washable FR fabric lost performance at 60 °C, highlighting the need to follow finish specifications (pmc.ncbi.nlm.nih.gov; pmc.ncbi.nlm.nih.gov).
Process economics push in parallel: counter‑current rinsing and heat recovery limit thermal losses, and dropping bath temperature by 10 °C can cut energy use by 15–20%. The trade‑off is kinetics; for instance, an enzyme that peaks at 60 °C loses much activity by 40 °C (pmc.ncbi.nlm.nih.gov).
pH control and neutralization
Correct pH is central to cleaning efficacy and fiber safety. Alkaline washes drive saponification and protein removal; caustic baths often reach pH 12–14, while enzyme baths stay below pH 10 (textilelearner.net). In many cases, efficient scouring without over‑attack sits at pH 9–10 (atlas-scientific.com), as extreme pH above 12–13 accelerates cellulose damage (textilelearner.net).
After alkaline steps (bleaching, mercerizing, urea/formaldehyde finishes), acid rinses — acetic or citric — neutralize alkali and stabilize the product, typically targeting mildly acidic to neutral pH 4–6. Buffered citrate is also used to rinse out excess anionic surfactant (patents.google.com). Wool and silk finishing often operates at pH 4–5 to swell fibers and remove knitting oils. Accurate addition helps keep these windows tight, and process engineers typically use metering systems such as a dosing pump for pH‑adjusters and auxiliaries.
Dye and fixative chemistry sets further pH boundaries. Acid dyes and cationic softeners favor pH ~4–6, while reactive dyes and many resin finishes require pH 10–11; final wash pH is chosen to optimize residual removal and avoid crosslinker hydrolysis in overly alkaline baths (atlas-scientific.com).
Baca juga: Dissolved Air Flotation
Rinsing stages and water quality
Effective practice is multi‑stage: an initial hot wash with detergent followed by one or more cold or warm rinses. Continuous rope washers commonly use 3–5 compartments with counter‑current flow to lift impurities efficiently (scribd.com). Thorough rinsing — often up to 5–8 bath volumes — drives residuals to negligible levels, whereas a second rinse alone may remove very little unless buffered and dispersed as in the citrate‑plus‑nonionic approach (patents.google.com).
Formulators also consider incoming water hardness, since high ionic content can tie up surfactants; hard‑water stabilizers (polycarboxylates, salts) are applied where needed. Plants that need to lower hardness upstream often evaluate softening technologies; a softener removes calcium and magnesium ions that would otherwise promote scale and interfere with wash chemistry.
Measured outcomes and verification
Cleanliness is verified by quantitative tests. Colorfastness is checked against AATCC/ISO methods, and whiteness or Tegewa ratings on cellulose quantify desizing; a Tegewa value of 6–8 indicates less than 0.1% starch residual (pmc.ncbi.nlm.nih.gov). Trials show that rigorous wash protocols — multiple rinses with dispersants — deliver more than 90% reduction in extractable finish versus baseline.
Surface integrity matters too. One laundering study observed no significant increase in fabric roughness after low‑temperature neutral washes, whereas maintaining temperatures above 60 °C or alkaline pH caused roughening due to residual detergent/mineral deposits (mdpi.com). The implication is direct: excessive heat or pH, without proper rinsing, can leave deposits that alter texture.
Baca juga: Sea Water Reverse Osmosis
Implementation summary and parameters
The data point to straightforward controls: select chemistry for the specific finish and enforce operating windows. On cotton, scour baths near 90 °C produce complete wax removal (textilelearner.net), while enzyme‑based scours at 60 °C can reach comparable cleanliness with less damage (pmc.ncbi.nlm.nih.gov). Maintaining wash pH around 9–10 — rather than pushing to 13–14 — balances cleaning with fiber safety (textilelearner.net; atlas-scientific.com). Combining a citrate buffer with a nonionic surfactant can remove over 80–90% of detergent residues that plain rinsing would otherwise leave behind (patents.google.com).
Where water quality variability complicates “as‑per‑water‑conditions” chemistry selection (crodaindustrialspecialties.com), facilities often standardize incoming quality. For hardness management at lower pressures than full desalination, some operations consider nanofiltration; in those cases, nano‑filtration is used to remove hardness while operating at lower pressure than RO.
Sources used for this guidance include industry and research publications: nepis.epa.gov; pmc.ncbi.nlm.nih.gov; mdpi.com; textilelearner.net; textilelearner.net; atlas-scientific.com; patents.google.com; crodaindustrialspecialties.com; peraturan.bpk.go.id; textilelearner.net; pmc.ncbi.nlm.nih.gov; pmc.ncbi.nlm.nih.gov; scribd.com.
